Prior to the island's construction by the United States government, "Yerba Buena Shoals" of rock[1] north of the transbay island had less than 27 ft (8.2 m) clearance and were a shipping hazard.[9] The 400-acre (1.6 km2) island was constructed by emplacing 287,000 short tons (260,000 t) of quarried rock in the shoals for the island/causeway perimeter rock walls (a freshwater reservoir was quarried in the rock of Yerba Buena Island).[9] Approximately 23 feet (7.0 m) of dredged bay sand filled the interior, was mitigated from salt, and then 50,000 cubic yards (38,000 m3) topsoil[9] was used for planting 4,000 trees, 70,000 shrubs, and 700,000 flowering plants.[1] Facility construction had begun by March 4, 1937 when two hangars were being built.

On Monday, February 18, 1939, the 'Magic Isle' opened[1] with a "walled city" of several fair ground courts: a central Court of Honor, a Court of the East, a Port of Trade Winds on the south and on the north: a Court of Pacifica, a 12,000-car parking lot, and the adjacent National Building, the $1.5M Federal Building, the Hall of Western States, the $800K administration building, various exhibit halls for industries (e.g., "Machinery, Science, and Vacationland"), and two 335-by-78-foot (102 m × 24 m) hangars planned for post-exposition use by Pan Am flying boats (e.g., the China Clipper through 1944[6]) using the Port of Trade Winds Harbor later referred to as Clipper Cove between the two islands. In addition to Building 2 (Hangar 2) and Building 3 (Hangar 3), remaining exposition buildings include Building 1 (Streamline Moderne architecture) intended after the expo as the Pan American World Airways terminal. The expo's Magic Carpet Great Lawn also remains.)[10]

A couplet from the song "Lydia the Tattooed Lady", in the Marx Brothers' 1939 film, At The Circus, reads "Here is Grover Whalen unveilin' the Trylon/Over on the West Coast we have Treasure Island", citing, in the Trylon and Treasure Island, two prominent features of international civic events happening that year (as the 1939 New York World's Fair vied for tourist patrons with the Golden Gate International Expo).

For the nearby former Hill Park military cemetery and the NRHP "Quarters 1 Nimitz House", see Yerba Buena Island.

Headquarters Building at US Naval Station Treasure Island

Treasure Island was originally intended to become a second airport for San Francisco, augmenting the existing San Francisco Municipal Airport, now SFO. But with war looming, the Navy moved in.

Naval Station (NAVSTA) Treasure Island began under a 1941[11] war lease as a United States Navy "reception center"[12]. On April 17, 1942, the U.S. Navy cut short an ownership dispute with the city by seizing the island[11]. The Navy eventually compensated the city with $10,000,000 in improvements to the existing airport, including reclaiming 93 acres of land, and postwar ownership of all military improvements[13]. (A widely cited Navy report[14] gave rise to the urban legend that the Navy swapped the island for land on which the city then built SFO. In fact, the airport has been operating in its current location since 1927.)

NAVSTA Treasure Island had a Naval Auxiliary Air Facility[5] to support helicopters, fixed wing planes, seaplanes, blimps, dirigibles and airships and a U.S.Navy/USMC electronics school. During World War II over 12,000 men a day were processed here for Pacific area assignments, and thousands more were processed for separation in the aftermath of the war.[15]

The psychiatric ward of the naval base at Treasure Island was used to study and experiment on naval sailors who were being discharged for being homosexual.[16]

In the '70s, '80s, and '90s the U.S.Navy conducted Naval Technical Training NTTC . Training Hull Maintenance Technicians. The U.S.Navy Rate consisted of the old Shipfitter Rate and Damage Control Technicians. The U.S.Navy Technical Training also included NBC Warfare Decon. The New U.S.Navy Rate was classified as HT Hull Maintenance Technicians. Multiple Maintenance Skills were included into The Naval Technical Training Command NTTC.[17]

Treasure Island beyond Yerba Buena Island's rooftops and trees, which obscure the causeway and marina. The large curved white building (right of center) is the Administration Building (Building 1) which housed the island's museum[22] 1976-97[23] (the museum association's offices returned in 2008.)[22]

By December 2010, Navy contractors had removed 16,000 cubic yards (12,000 m3) of contaminated dirt from the site, "some with radiation levels 400 times the Environmental Protection Agency’s human exposure limits for topsoil."[27] The contaminated dirt is to be replaced by dirt removed during construction of the fourth Caldecott Tunnel bore. In April 2013, caesium-137 levels three times higher than previously[when?] recorded were found (the island hosted "radioactive ships from Bikini Atoll atomic tests and [was] a major education center training personnel for nuclear war"[28]—the USS Pandemonium (PCDC-1)[29] mockup had begun nuclear training in 1957.[30][31]

SFUSD previously operated Treasure Island K-8 School. In Spring 2004 the SFUSD board voted to close the middle school portion but keep the elementary school in operation. In its final semester of operation it had 95 students. In December 2004 the district voted to close altogether effective the beginning of 2005. Initially the Treasure Island Homeless Development Initiative fought to save the school, but after discipline and staffing issues occurred in 2004, the group stopped its efforts. Heather Knight of the San Francisco Chronicle wrote that year "Even people who had fought to save the school earlier this year now admit it's no longer worth saving."[33]

The main waterlines under the causeway are backed up by yellow above-ground emergency manifolds to which blue six-inch (150 mm) diameter hose can be connected from a large hose spool affixed to a San Francisco Public Utilities Commission / SF Water Dept' mobile truck dispatched from the SFWD Newcomb Avenue Yard after an earthquake, provided the Bay Bridge from SF to Treasure Island is still operational.

^ abcdeMcGloin, John Bernard. "Symphonies in Steel: Bay Bridge and the Golden Gate". The Virtual Museum of the City of San Francisco (SFmuseum.net). Retrieved October 22, 2013. The Secretary of War approved the request that its execution be undertaken by the Army Corps of Engineers. While a group of such specialists applied their talents to the reclamation of the 'Yerba Buena Shoals', the day-by-day details were efficiently cared for by Colonel Fred Butler, U.S.A., who had years of army engineering experience behind him at this time. The fill to form Treasure Island was obtained by dredging operations; the island covered an area of 400 acres [160 ha], 5,520 feet [1,680 m] long by 3,410 feet [1,040 m] wide.

^Smith, Matt; Mierskowski, Katherine (April 12, 2013). "Soil tests find cesium, linked to cancer risk, up to 3 times higher than previously acknowledged". The Bay Citizen. Retrieved October 26, 2013. Until the early 1990s, the Navy operated atomic warfare training academies on Treasure Island, using instruction materials and devices that included radioactive plutonium, cesium, tritium, cadmium, strontium, krypton and cobalt. These supplies were stored at various locations around the former base, including supply depots, classrooms and vaults, and in and around a mocked-up atomic warfare training ship—the USS Pandemonium.